The tragic loss of over 250 lives in underground mine fires in West Virginia, Kentucky, Mexico, and China in late 2005 and the first half of 2006, has revealed a serious deficiency in terms of emergency response.
Typically when a mine accident occurs, there is a failure to locate and rescue underground miners surviving an explosive accident in time. Days, not hours have been necessary to get rescue teams to the scene, locate any survivors, develop a safe plan, and save the survivors. To mine survivors, awaiting rescue is a life-threatening ordeal, especially when they cannot communicate with the surface that they are alive and where they have taken refuge. After underground mine collapses from explosions, seismic activity or other causes, escape paths are probably blocked. Miners are trained to barricade themselves in a habitable atmosphere available while awaiting rescue. Once safe, survivors attempt to communicate with the surface about their location, number of persons, and status. Often, hardwired mine communication phones are knocked out, or are unreachable, because of the presence of deadly gases in the post-explosion atmosphere, or because of blocked passages by rock debris. When denied or separated from communication equipment, miners resort to desperate, archaic communication techniques, namely, pounding on steel structures (plates or rails) with hammers to attempt to send acoustic signals to rescuers within audible range above. However, all too often, mine rescue teams are not within this range because these signals are usually too weak to be detected on the surface.
Two-way wireless electronic communications systems are being considered as upgrades to existing hardwire mine communication phones. However, these advanced systems have similar problems associated with hard wired systems. They also need to be interconnected to the surface from the miner locations underground via mine passages, which are now blocked. More failsafe, alternative communications devices are urgently needed that communicate form the underground to the surface after the collapse of the mine passages.